Composite blocks of adsorptive material are useful as filtration media in the treatment of liquid feed streams such as in water treatment applications, for example. In such applications, composite blocks can include activated carbon particles that are bound together by a polymeric binder material such as one or more polyolefin materials including ultra high molecular weight (UHMW) polyethylene, for example. Composite blocks provide treatment capabilities comparable to and often better than those of a loose bed of carbon particles when used in the removal of organic contaminants from water. Moreover, composite blocks are compact in their construction and can be handled with a reduction in the mess commonly associated with the handling of loose beds of carbon particulate.
Composite blocks may be made for use in any of a variety of filtration applications by including appropriate components in the construction of the block, either in addition to activated carbon or in place of it. Such components can include, for example, ion exchange resin, adsorbent materials; metal ion exchange zeolite sorbents; activated aluminas; silver, zinc and halogen based antimicrobial compounds; acid gas adsorbents; arsenic reduction materials, iodinated resins, textile fibers and the like.
Although composite blocks have been widely applied in a variety of filtration applications, the technology has suffered from long recognized limitations. One such limitation has been in the treatment of filtration feeds having high sediment content. Composite block filtration media that comprise activated carbon have been used for the purification of residential water at the point of entry (POE) to a home, for example. Residential water supplies can have high sediment content, and filtration media comprised of composite block filters (e.g., blocks of activated carbon) have suffered from a low tolerance for such sediment. As a result, composite block filters can completely foul (e.g., become obstructed) within relatively short periods of time following an initial exposure to a high-sediment feed stream containing silt, iron or the like.
A long felt and unmet need has persisted for a composite block construction useful as filtration media which is more resistant to fouling when used in the treatment (e.g., filtration) of feed streams having high sediment content, for methods of making such composite blocks, and for filtration systems comprising such composite blocks.